in 3D - Section Box all measurement tools are grey indication of no use/doesn't applay/stay away/? Using 3D-SB you can have a glance insidea 3D modell and there be objects that only have a elevaton and no other properties except New Constuction (Specialty Equipment). So confirming space is a pain.
You can add dimensions in 3D views to check distances. Don't have access to Revit at the moment, so I can't confirm whether or not you can use the measure tool in 3D views.
You can still do dimensions in a 3D view with the section box turned on, but you can't use the measure tool. You'll have to cut an orthographic view (section, detail, plan, etc.) to get what you're looking for.
do you want to put dimensions in 3d section of on object in 3d view ?
You can do it using a small trick: