Available with the ArcGIS Indoors Spaces extension.
You can measure spaces in 2D and 3D using the Measurement tool 
. You can draw a polyline to measure distance or draw a polygon to measure area and perimeter. The default unit of measurement is automatically applied from your ArcGIS organization profile. You can change the unit of measurement while making measurements. When the tool is closed, it reverts to the default unit of measure.
The Measurement tool is hidden by default. You can configure visibility of the tool in the Configure App panel.
Note:
The accuracy of measurements depends on the underlying data and coordinate system of the map.
The Measurement tool is available on tablet devices but not on mobile devices.