I wouldn't recommend disassembling a microwave oven to get at its magnetron, because you will probably electrocute yourself at best, and if you manage to turn it on (e.g. by jamming the door closed sensors), literally cooking your eyeballs.
I've got a friend who claims you can force a DJI drone to autoland from well over 1km with some microwave oven guts duct taped to a satellite tv dish.
The word you're looking for is "maser."
It's true though that both of them are coherent microwave sources. And the magnetron is arguabbly more "laser-like" than a maser.