Some use a arabic numerical system to identify the placement of notes. You can learn to sing numbers. I think this is helpful when constructing chords as well as remembering melodies. A basic form of this is how they show children to tap out numbered bells which can be applied to keyboard identification.

In place of writing notes on a staff to learn a new tune, I use arabic numbers attached to rhythmic symbols if I don't have time to scribble out five lines of a musical staff.

I assume that the question is about learning to internalize music by hearing it and identifying what is heard.

Frank Hamilton