For me: alt+enter (switches to Greek keyboard layout), m, alt+enter (back to usual layout). I use Greek symbols in Python and in Javascript. I do it almost without thinking now, as lots of my coding is tightly linked to maths.
you can map a useless key like capslock to do that in a single step. Thus to type μ, for example, you simply press CAPS+m, and similarly for all greek letters
What is a capslock key, I only have ctrl and hyper ;)
man, it's the only key that has an assigned light in my keyboard! Funnily, the capslock light in my laptop seems to be detached to the configuration of that key, so that the light shows the parity of the total number of greek characters that I have typed.
You probably have what is called a GUI key, hyper died out with the space cadet keyboard. Caps lock is above the left shift.