A CNC probe is pretty darn expensive, a few hundred of USD, and for a reason, they do a great job, they are pretty finicky things to make, they last for ever (or until you crush them by mistake because you forgot to plug their cable in before launching the cycle)


Now you can 3D print your own CNC probe that works in X, V and Z, you will also need to buy some inserts (Metric 3mm) find yourself a reliable spring that can push 1Kg when compressed 10 mm, inner diameter of the coil 12mm total length 25mm, and obviously 4 M3 bolts long enough to do the job (20 mm)

In the end you need a probe Stylus from internet, and an insert that matches it's thread (I tried 2.5 metric and it works, but for more solid jobs Metric 4 is best)