Adding Costum Sensor to Cube/Herelink

Hi all!
for a project, i want to add a costum build sensor to a uav using the following components:

  • Cube Orange flight controller running ardupilot

  • Herelink HD video transmission system (both airunit and remote controll).

So far, i would be flexible regarding the communication protocoll, but i can’t find out whether the sensor should be connected to the herelink or the cube, which connections can be used and how to add my aquired data to a communication protocoll in order to transmit the data to the rc control unit.

Thanks in advance!