2018 Ford F-150 - Whistles

My truck makes A high pitch whistling sound when it is parked, not running and keys removed. seems like it is getting more frequent . any suggestions???

Yes, tell us what engine you have, how many miles on it, any check engine light, 4WD or rear wheel drive. And more about the noise. when it started, does it always happen ect.

Let us know if it turns out to be any of these noises vehicles make when off.