Something I'm learning about Mantis,is those like you have will normally shy away from your fish and most of your other inverts.
I know because I got one just like him living in my tank.:D He'll display at the fish and cleaner shrimp until they get to close for his comfort,then he'll dive into a hole.He usually comes out at night and hunts for pods along the rock.
But if you really want to catch him,you'll have to spend a little time and get him used to being fed from a net or in some other type of trap.Then when he's comfortable being fed,you'll have to quickly yank him out.BUT,You'll have to get him on the first try.After that,you'll have to come up with another idea.
