Buzzing and static noise outta the 85W adapter, should worry?

Thanks for reading this whatever who you are, I'm having a MID2014 15inch MacBook Pro with the GT750M, the adapter is about a year old, it's a swap one from genius bar becuz the original one is falling apart.

i noticed that there is a buzzing noise coming outta the adapter when i cleaning the dirty adapter in a complete silent room, and the noise do changes with the system load and charging status, it is kinda weird to describe, its somehow sounds extremely alike a loading hard drive when system energy load changes( like i start up a graphics intensive game).

And we know even though the Retina MacBook Pro is fully solid state, but you can hear there is some static noise coming out from the computer if the system load is changing when you using it in a silent room, this exist on every single one for no doubt, its not the fan, I've tried out a tons of 15 inches, this is quite regular and nothing to worry about. B!U!T! this static sound in the computer will be enlarge when i connect the adapter.

then i robbed my friends totally same but brand new 85W adapter, which is came with her 2015ver of the 15inch and its only days old. its have kind of the same noise, only the loudness a bit lower than mine.

for both adapter, its only noticeable when put against the ear (i use extension wire in the box with proper grounded power supply), just mine older one is a bit louder maybe just becuz of its a year old. Its functions no problem as far as i can see, i might just a paranoid XDXD, but i basically use the computer in a silent midnight alone in my apartment every single day, and my ears just somehow sensitive with extreme high pitch sound, so it might making me more concernedXDXD, but just want to know, should i be worried about this or its totally fine, harmful or not? if you have a 85W too and using a extension wire, may i bother you also put it up to your ear and if the same noise😊? and any other mid night use like me that hearing the same thing? sorry for the gigantic paragraph XD