Have you ever sat down to sketch because you just felt like sketching something, but did not know what? That is what happened with this piece.
I just sat down and began sketching. I started by drawing an eye. I had no plan and was just messing around. After I finished the eye, I still felt like doing more sketching, so I started on the nose. After the nose was drawn, I moved on to the mouth. And so on, and so on, until eventually this sketch fell out of that process.
It is was done digitally using a "pencil" brush. It is meant to be a bit rough, not completely refined. I actually like the look of a slightly rough sketch. Not messy, but not completely refined either.
Most of the time, I use an iPad Pro with an Apple Pencil and the application Procreate to create digital artwork. I like this combination because it is like having a digital sketchpad that you can carry around with you fairly easily at all times. It is easy to use wherever you like, at a table, on a couch, while lying in bed, outside sitting in the shade, and so on.