This video demonstrates a simple fox hunt transmitter using a Baofeng UV-5R and an MP3 player connected with a Baofeng APRS-K1 audio cable.
Please note: If your MP3 player is causing the PTT to stick open, try putting the Reverse Connector Adaptor in between the MP3 player and Baofeng APRS-K1 audio cable. The MP3 player I used has a record function and you can hook an external microphone up to it. If the MP3 player you’re looking at cannot have an external microphone, it might not work.