You can try a piece of shrimp, tied to a small rock, in a plastic bottle with the spout cut off.
If you can prop it close to where he resides, better, if not, on the bottom.
If its propped up in some way to the rock, he may go in but can’t get out.
Hit and miss but the least intrusive.
In the end, if you have any opportunity, take it, spear crabbing is an option and fish get dinner.