Getting rid of Voles & Moles
Traps are the main "trick" to decreasing moles and voles.
These creatures make different kinds of holes. These publications will help you differentiate between them and use the appropriate kind of trap.
Voles are easy to trap, moles more wily. You can repeatedly trap voles with a mouse trap placed at the hole entry. Mole traps require more muscle power to set; you may want to hire someone for the job.
"Controlling Moles" https://wildlife.unl.edu/pdfs/moles-and-control.pdf
"Controlling Vole Damage" https://wildlife.unl.edu/pdfs/controlling-vole-damage.pdf