Stationary tool probe question

[xeno-kalo]

Hello everyone,

I recently purchased a tool probe which inside the housing contains a basic switch (can be wired NO or NC).
I have the tool probe bolted down on my machine bed's top right hand corner.
I use GRBL and UGS to control the machine.

I am trying to use the probe to help me semi-automate tool changes.
Can any one you confirm if the below workflow is achievable with GRBL + UGS combination ?

1. Manually Load Tool 0 in the spindle
2. Manually set Z=0 on my stock
3. Probe the Z axis using my tool probe
4. Manually Load Tool 1 in the spindle
5. Probe the Z axis again
6. Calculate the difference in height between the 2 tools used

No matter how hard I tried I couldn't come up with a method to exclusively achieve the above using just WCS's...
Any tips? is this even possible to do? or there has to be a mathematical operation for this workflow to become feasible ?

All the best
Xeno