I think this one is from SketchUcation.com Plugin Store.
Register (free), login, then search and download. Or better, first install SketchUcation's own plugin to manage and update all their plugins, then use that to search the store and auto-install.
Mostly, I put dimensions on their own layer or layers. You can add them within a component, and even if you don't they usually move with the points they are attached to.
There's also a plugin called ToggleTextAndDims which sits in the View menu and will globally toggle text or dimensions (separately) on or off.