“Dropped Phone Alert” setting or app? Better alert if phone goes out of bluetooth range

I was recently trail running in an area with no cell service.

My phone bounced out of my pack pocket, and I didn’t notice the quick “Connection lost” message and buzz, if it even came up during an activity.

Find My Phone did not work, but luckily someone found it and picked it up, and as soon as they got in cell service the Find My Phone worked.

i think a “Dropped Phone Alert” setting or app would be very useful. I’d like to see an alarm like an incoming phone call or a wake-up alarm when this setting is activated and the phone goes out of Bluetooth range. 

The regular notification and light buzz isn’t enough if you’re mountain biking or running technical trails.