I've tried these as apps before, and they never worked that well unfortunately. Perhaps the ticks aren't loud enough, or phone mics aren't that great, or background noise gets picked up as ticks, who knows.

I bought and use the item linked below. It's big, and feels like tech straight out of the cold war era, but works great.

https://www.amazon.com/gp/aw/d/B0081SSJZG