Hole in Soil Appearing
That looks like a rat hole to me. I've had them on/off in the back garden for over a year. I put some bait down and see if it goes. Keep filling the hole in, if it reappears with similar shape/size you can be almost sure it's rats
It's far cheaper to buy a rat bait box and the bait to DIY rather than calling in a professional. It's quite easy to do if you follow the instructions, wear plastic gloves (and throw them away after use). The rat (if it is a rat) will go into the box, eat the bait and go and die elsewhere.