Your best bet is to leave him where he is. Especially if he is this small.
Someone brought this little guy into the shelter. A child had found him in a pile of leaves and decided to bring him in the house. It’s almost ALWAYS best to leave these babies alone. They called me to see if I could foster him until he weighed enough to set free in a wooded area. I called the Alabama Wildlife Rescue Center and followed their instructions. I put him on a low heating pad with a soft blanket, harvested some grass and clover from the vacant lot next to my house (not treated with pesticides), soaked them in water and put them near his tiny mouth.
He never touched the food and he wouldn’t take any water from a dropper. Despite my efforts, he didn’t make it. They almost never do when they are so small.
I take solace in my healthy and happy pets, and make a wish for those not so fortunate.