Here's a trap someone showed me. Have never had to use it but it looks like it would work well
You cut the top off a 2L bottle and reverse it. It should stick inside without glue or anything. I suggest not using tape if you want to stick it together. Anyway you just throw a mouse in and maybe even a heat pad under it. The snake will be funneled in, but once he gets in it will be hard to find the hole he came in from. Chances are he'll eat the mouse and be stuck.
Here’s a bad picture to help explain it better. Good luck!