If he shaves his head they will take chest hair or pubic hair.
then the hair will show when he was using and when he was not over a period of time. Same thing if he doesn't shave his head. It is a more accurate test than a UA and he has a harder time 'beating' the test.
The only reason it is not used more is the 'cost' of the test. I am glad the Judge chose to have this type of test done on your H.
Hopefully when the judge sees the results he will change the 'visitation order' to 'supervised'!
Love and hugs,