Here is the link to the app on the play store:

https://play.google.com/store/apps/details?id=com.infomultiverse.btscanner

Here is a short video Demo of the app:

It was mainly designed to find your lost misplaced fitbit, smartwatch, gear or other Bluetooth enabled equipment. However, it can be used to sniff out any Bluetooth device like a smart tag planted by thieves, or you can simply use it to actively monitor and keep an eye on your Bluetooth Devices.