I used to be a scratcher and would be semi conscious about my scratching as an alternative I've started cleaning out the undersides of my finger nails by picking out dirt that may not look like it's there but you can somehow feel.
Some other habits I have when I'm anxious are rapid leg movements causing me to look as if I'm vibrating, shaking and twitching (my head twitches the most I'd say), I sweat on the bridge of my nose so I continuously scratch it, and I become very hypersensitive or self aware (I feel my lungs moving in my chest, hear my heartbeat in my ears, and become slightly numb all over when focusing on certain areas)