Invisible mob and the skulk sensor as an item

So, the skulk sensor is able to hear sounds, but it does not do that when you hold it out in your hand on your hot bar. What if the sensor could be crafted into some kind of a device that detects infrasounds or ultrasounds, you know, sounds that are beyond the human hearing, or, Minecraft character hearing. That thought got me thinking that there could be an invisible mob somewhere like the deep dark, maybe the new dimension, that you can discover with this listening device. Obviously, on its own such an idea seems like a needle in a haystack type of situation, however maybe there's like abandoned camps where these invisible characters are hiding, maybe there could be like a skulk sensor that rustles every once in awhile as a cue to the player that there's something there, hiding. The invisible character could be someone who used to live in the ancient city, a runaway from the warden perhaps. Idk, seems cool.