“How do you get police scanner app?”
There are quite a number of them available for all mobile platforms (e.g Scanner Radio). Just have to search for “police scanner”. Of course whether the local PD allows the feed is another story.
Also various websites have the feeds. Just type in “police scanner online” in Google and there will be lots of choices. Unfortunately it is still a story of the PD letting that feed go out. Many of them are on delay and can be cut at any moment.
Thanks re: police scanner!