Help! Thumbsucker in the works

Kianna

My son.has recently discovered his hands and.boy.has he been.happy. however my.little pumpkin has also discoveredthe way to.his mouth and.is.constantly.sucking.on.his hand. Any remedies to.prevent this. I habe tried.talking, taking.the hand away several.times.and are all out of.options.i need help desperately