How to use extra channels in drone controller for other purpose
The 6 connecters on the receiver have 3 pins each. +5v Signal Gnd

The signal is an output that is Pulse Width Modulated PWM / Pulse-Position Modulation PPM. Such that it pulses on to 5v and back off to 0v(GND) at a frequency 50hz with a pulse on the duration of between 1ms and 2ms with the length indicating what the value of the signal sent from the transmitter is.

How to get the PWM frequency and duration of each pulse?
https://learn.sparkfun.com/tutorials/hobby-servo-tutorial/all