To help stop baby's thumb sucking

I’m having a problem with my baby’s thumb sucking. Before, I wanted to purchase a product that will stop his thumb sucking but since my funds were limited, I wasn’t able to make it. Until these past few days, I was wondering the reason of his thumb sucking. I tried to observe him and find out that he will just thumb suck if he’s holding a piece of cloth (piece of towel or a bib). So, what I did, I just hide all of the small pieces of cloth and observe him again. It’s then I know that he will forget his thumb sucking if he can’t see any of these things. So, right now, even if he is having a hard time taking his nap or sleeping at night, I will still not give piece of cloth for him. This is to help him have a nice shape of gums and teeth! And today, I’m still observing him and hoping that he will totally quit his thumb sucking.