With ProbeIt, run your perimeter routine, writing to a DXF. When finished with the perimeter, DO NOT CLOSE THE FILE.
Now change to the Surface X/Z page and do your surface probing. The Z data will be written to the original DXF. Now you can close the DXF, and view as 3D in your CAD.
I use Probeit for edgefinding, centering, bore and post indicating, confirming tram and lots more. Best $30 ever.