The Note Names & Finger Number System (NN/F#). By far the most common way to learn a song for the non-reader. This system is simply the letter name of the note with the 1st position finger usually associated with it. Here is a chart of all the first position notes in this system.
The only lacking point in this system is that is does not show any rhythmic values. This you’ll have to glean from the staff notation, or by listening to audio tracks. The positives of this system are that, unlike Fiddler’s Tab, you actually know the real note names, which at least puts you “in the club” when you need to speak to other musicians about what notes you are playing. I encourage my private students to learn standard staff music as soon as they are ready, but start them out with this NN/F# system, and often continue to teach them fiddle tunes this way even after they’ve learned to read.