Most furniture stores have markers (they look just like a highlighter fat marker), they come in sets, and have several colors in each one. I've had a set for years, and they are wonderful for covering scratches and dings.
I like that you can have a choice of shades, and I've even mixed them, one color on top of another to get just the right look.

I have a different brand, but they are similar to this. I find this is easy to control and you can mark just where you want
I've used these on furniture, wood cabinets, wood floors, anything wood that needs a touch up.