There's actually some research out there that shows doing little inane things like this helps people to focus. There was a study done a while back on doodling, even just utterly pointless scribbling and it helped people stay mentally on task. Now obviously, if you're supposed to be typing or something like that, it's going to be a problem.
I teach a handful of teenagers and just started handing out those "adult coloring" pages a month back. Attentiveness, responsiveness, and retention in my class have gone through the ROOF. Whereas these kids, (some late high-school others early college. All under heavy class loads, and a number working jobs besides) previously could hardly keep themselves awake or focused at times. It's been a real boon to give them a bit of fidgety stuff to do.
Yes you can just click that 25 cent pen. I handed out clicky pens to my class a while back. They clicked and clicked... and clicked those pens. And I had to try not to set fire to each and every one of my students that day. If you work alone, go ahead and click your pen. If you work with other people, STOP IT!