Use a net, the bigger the better. Leave it in the tank at a corner at the bottom with the handle up. Set it up so it's almost flat against the glass and only kicked out slightly. Use your magnet cleaner as a support aid. When you feed put food in that area and get food inside the net a little. Eventually the wrasse will wonder in, when he does run up to the tank and tap the glass which will scar him back further into the net. Turn the net handle so to trap it against the glass, pull out net and fish
Worked for me every time, might take a day or two but I caught wrasses, tangs, and angles. The wrasse was the easiest. A fish trap won't any better.