I have played around with many solutions for this. I suggest planning and experimenting as you go to get the perfect result. The thing I think that would work best is making your lines in permanent marker and then putting a clear adhesive tape over the entire staff to protect it but still allow you to write and erase on it.
One thing to consider, is what is the perfect size of staff that will be comfortable to notate on and give you enough room to capture your idea. You may want to experiment by printing out some staves of different sizes on paper and trying it out. You can build your own staves from scratch in any word processing or layout program by creating some lines with the line tool and then adjusting the line thickness or font depending on whether you used a line tool or the plain underline. I like indesign for this because I can do step and repeats to create the exact distance between lines that I want.
Permanent marker lines (Sharpie) are probably the best if you’ve really decided that you want it on the whiteboard. You can use masking tape to lay out your lines before you draw them. The masking tape will make it easy to make a straight line and also to get a consistent distance between your lines. If you get the standard 3/4 width masking tape, probably one deep would be a good distance for your spaces. I recommend getting the masking tape near the paint section or at an artist supply so that you get low tack tape, meaning it will come off easily without leaving a sticky residue on your board. I’d measure from the top or bottom of your white board at various points and mark it so you can get your lines on the board straight.
You can get clear adhesive laminate tape in a roll that and put that over the top. (The tape should be glossy not matte so you’ll be able to write and erase on top of it.) Here’s a link for something that might work:
It doesn’t have to be that particular tape. I grabbed the first link I found just to give you an idea. You can shop around. I think using a decal or stickers to lay out the lines is going to be a lot of work getting straight and lined up properly. I’ve put pinstriping on a car before. It’s NOT easy to do a great job. Also, decals will make it bumpy to write on.
I’ve also created smaller page size whiteboards before by printing a staff on it and then laminating it.