Who can I call if I think I have a rattlesnake in my yard. I can't see it but I can hear it

Maricopa County Animal Control does not deal with snakes.

You can call the nearest fire department, they are trained for that too

Google snake wrangler and call them.

You would want a pest control company. Despite the name, Maricopa County Animal Care and Control only deals with live dogs and cats and no other animals. They will deal with smaller wildlife if it's a matter of rabies testing following a bite to a human from wildlife or a pet being exposed to smaller wildlife where rabies contraction is possible.

Animal control but they will take forever. Call non emergency police line and ask