Catching my hitchhiker crab

[foxy9]

My reef tank has been running for 3yrs. I spotted a "cute" little crab(the size of my thumbnail) at the the top of my live rock, I tried to catch him for a week, and then I didn't see him again until last week. Well fastforward 3yrs, and he isn't very small anymore and he isn't very cute either! lol
I don't know what sparked him to come out of hiding after all this time, but for some reason he isn't shy anymore. I NEED HIM OUT.
He doesn't come out beyond the caves of my live rock so I can't net him,....how do I trap him?