I would trap him. For example, take a 2liter pop bottle, put some fresh seafood in it, and put some filter floss stuff in there as well for him to "hide" in. If you don't feed the tank for a few days ahead of time, the worm will be very hungry.
When he goes in to get the seafood, which of course will smell very tantalizing to him, you go after the end that is not in the trap, and he will pull that end into the trap to "hide" in the batting, at which point you pull the pop bottle out with the worm in.
I used a variation to get a 6-inch worm that ate a peppermint shrimp out of my 6 gallon -- I put scallop in the turkey baster, the worm crawled up into it, and I pulled out the baster with worm inside.