Read previous reviews and chose this app rather than paying $5 for the FitBit finder. Turn the sound on. The app will detect any Bluetooth device. Select the device you want to search for, otherwise you will hear beeps from each device. The app identified my FitBit as "One"--other devices had names or a series of numbers. When the beeps become more frequent and higher pitched, you are getting closer. Watch the decibel number too. Far away, it will be a negative number like -94. Closer, it will drop to -67. At this point, set an alarm on your FitBit. Hopefully you will hear it like I did. I found my FitBit in the pocket of my bathrobe that was hanging behind my bathroom door.
AmyDM127 about Bluetooth Smart Scanner