For spatial data to be displayed in 3D, you must set height options. This includes defining the feature layer's base height and vertical units as well as optionally defining a cartographic offset. Base heights determine the lowest elevation of features in the layer. A cartographic offset can be applied to adjust where features are drawn vertically relative to the base height.
2D and 3D categories of a scene
The Contents pane of scenes includes two sections: 2D Layers and 3D Layers. Layers in the 2D section are on the ground, at an absolute height, or on a custom surface. Layers in 3D can be relative to the ground, relative to the scene and relative to a custom surface. 3D symbols can be applied only to layers in the 3D Layers category. You can drag layers from one category to another in the Contents pane. Different elevation modes are available for layers, depending on whether the layer is in the 2D Layers category or the 3D Layers category.
For layers to appear 3D, use 3D symbology, and display properties, the layer must be in the 3D Layers group of the Contents pane. If points in a feature layer appear sunken into the earth, check the anchor point of the symbol.To place points on the ground, move the anchor point. Open the Format point symbol mode of the Symbology pane to resolve this issue.
Vertical coordinate systems
It's important to define a vertical coordinate system when working with 3D data. If the data source of a layer has a vertical coordinate system defined, the elevation unit of the layer is the same as the linear unit of the vertical coordinate system.
Tip:
To see the vertical coordinate system defined for your data source, or to see whether your data source has a vertical coordinate system defined, right-click the layer in the Contents pane, and click Properties. On the Layer Properties dialog box, click the Source tab and expand the Spatial Reference heading.
When importing an ArcScene file (*.sxd) or an ArcGlobe file (*.3dd) or opening an older ArcGIS AllSource project (*.aprx file) prior to ArcGIS Pro 1.4, the elevation unit is not set to the vertical unit of the vertical coordinate system of the data source. Use the Project tool to project the data to another coordinate system if necessary.
Elevation types
To set the elevation properties for a layer, right-click the layer in the Contents pane and click Properties. On the Layer Properties dialog box, click the Elevation tab. The following options are available:
- On the ground
—For features that are situated at ground level, such as trees. 
- Relative to the ground
—For features that are placed at a known height above the ground, such as security camera positions on the side of a building. Use the feature's Z values or use the Feature Z profile to create an Arcade expression to adjust feature Z values.
- At an absolute height
—For features that occur at a constant height above a datum, regardless of ground elevation, such as airplanes. In addition, you can add a vertical exaggeration to the absolute height. This way, you can make differences in the elevation more prominent. For elevation surfaces, you set the vertical exaggeration as a property of the map. Use the feature's Z values or use the Feature Z profile to create an Arcade expression to adjust feature Z values. When a feature layer doesn't have geometry z-values, this option is not available when setting additional feature elevation. 
- On a custom surface
—For features that occur on a surface not represented by ground level, such as a well site intersection on a subsurface geologic plane. You can choose a custom elevation surface from a list of defined surfaces in the scene. You can choose this option when no custom elevation surface layer exists in the scene and this will create a custom elevation surface layer with this layer as the elevation source and define its height to the custom surface. 
- Relative to a custom surface
—Where additional height values are added to the feature's location on a custom surface. You need a custom elevation surface to use this option. Use the feature's Z values or use the Feature Z profile to create an Arcade expression to adjust feature Z values.
- Relative to the scene
—For features that know where they are compared to the scene. These features align to the ground and 3D objects such as extruded polygons or buildings.
Cartographic offset
A cartographic offset vertically adjusts the z-value of the entire layer. This raises or lowers all features in the layer by a given height. It is useful for cartographically elevating a set of features in a scene to make them more visible. For example, you can raise point symbols representing fire stations off the ground so they aren't obstructed by surrounding buildings.
Multi-select elevation mode
You can multi-select layers in the 2D and 3D Layers category and update the elevation mode. For example, you can select three raster layers and open their layer properties to update their elevation mode to On the Ground. The Relative to the Ground mode is not supported with multi-select. At an absolute height supports z-values and not a field.
Elevation context menu
You can use the elevation context menu on raster and TIN layers to add them as elevation surface and source layers. Use Duplicate in Ground 
to duplicate the layer in the ground elevation surface layer. Use Create Surface Layers From Sources to create a custom elevation surface layer and add the selected layer as an elevation source. You can set the elevation mode of the selected layer to the newly created custom surface on the Elevation page of the layer properties.