How exactly do Spirits leave messages on Microphones/Camera?

I just wonder how this happens? E.V.P.'s are cool.

By the way I believe reincarnation provides more convincing evidence
than any other religious belief and it doesn't threaten those who don't believe!

I studied the Catholic faith and many others.

[Apex]

I would assume it has to do with some kind of manifestation of energy, but I hear this is very difficult and draining for spirits and other various nonphysical entities to do.