Sucking his thumbs

Most infants start sucking their thumbs at this stage. This is the only play available to them. My son is also putting his hands and fingers into his mouth. It is so cute to watch while he was helping with one hand to put another hand into mouth. How to prevent this habit? We don't know how to. We just wrap around his hand with a cloth. It is annoying for him. He cries when he was not able to put his fingers in mouth. I think he associated thumb sucking with hunger and milk feeding. Whenever he feels hungry he sucks finger.