Put the mouse/vole back where you found it. It's a wild creature, not a pet, and would feel like a prisoner if you took it home and put it in a cage.
You are not allowed to take a mouse/vole on a plane. It will be illegal to take into the cabin, and you certainly can't pack it in your checked baggage. The creature would need to be totally secure and that means shutting it up in a box. You won't be able to take it out of the box, and how will it eat and drink in those conditions. In addition, the poor little thing will be absolutely terrified.
Just put it back in the wild where it will be happy. Yes, snakes could get it - that's life - but it could also lead a very long (for a mouse/vole) normal life with creatures of it's own kind. You're not thinking of the welfare of this creature, but selfishly thinking of how you'd like to look after it. Taking it away from it's natural environment is inhumane and cruel.