Blender Workflow:

With the Geometry Nodes feature that the Blender Foundation implemented recently, it's now possible to apply a displacement in brute-force way and use it to create a calibrated Ztool.

Download the sample scene or create this nodal tree with the Geometry Nodes.

- Open the scene and import the head geo. (XYZ_headEyesOpen_GEO.obj for egs).

- Click on the Geometry nodes tab.

- Click on the "Browse node tree" button and select the "subd_from_map".

- On the geometry node modifier properties context, click on Vector and choose UVMap.

- Load the "XYZ_dispCalibrated_mid0_raw.1001.exr" file to the Image Texture node:

 - Change the Subdivision Surface value to something like 5 to reach 17 millions polys:

- Finally, Export your selected geometry in OBJ:

- Open Zbrush and import the geometry previously exported from Blender.

- Go to the Geometry tab and hit the "Reconstruct Subdiv" button multiple times.

You are done! Your calibrated Ztool has been reconstructed, will 6 subdivisons and 17 millions polys in just a few minutes!