I'd suggest catching it in the middle of the night when the wrasse is fast asleep. These wrasses typically sleep under rock shelves, under corals, on the sand surface or in a crevice. Generally they do not bury themselves in the sand at night like other wrasses do. I'd watch to see where it sleeps at night. You can either watch to see where it goes when the lights go out. Or get a red light and look for it in the middle of the night (with all while lights off both on the tank and in the room). Catching a sleeping fish is much easier then during the day. Even catching a newly awoken groggy fish is easier then one which is a wake and moving fast.
If it is in a crevase, set up a QT tank, have it running and ready. At night take the rock with fish out and place into the QT. The next day when the fish has left the rock crevase, take the rock and place back in the DT. It will be much easier catching a fish in an empty QT using a couple of nets.