How would I add custom frequenzies to the vanilla Calibrated Skulk Sensor?

I want more options for the Calibrated Skulk Sensor, like it detecting the player crouching/ sneaking or whatever else one would need. I still want it to be the "vanilla" sensor, so that if the World would be loaded into vanilla the sensor would persist, just lose the added detection capability. 

I'm completely new to modding and mcreator, looked everything up I could find with my limited knowledge, but I know too little to effectively find info.