Velcro detergent cup to the side of the washing machine

A few weeks ago, the measuring cup for the laundry detergent mysteriously disappeared.
My husband joked that we should Velcro the next one to the side of the washing machine, so we don't lose it. I thought that was a brilliant idea.
This only makes sense if you use the same detergent all the time, or have a lot of little Velcro stickers. I put the fuzzy side on the machine and the hook side on the cup, but it probably doesn't matter much which goes on which.