For contest it is usefull to have headset, so you have "hands-free" operation.
Cheap headsets are such for gaming or communication with the PC.
They use electret microphones, wich need voltage for working.
Most HF-Transceivers deliver Voltage on the MIC connector.
Here is an example for building an adapter for use PC headset with Kenwood radio.
the wiring
check several headsets for good sound, have fun!