Field in Dashboard that displays on front end

I’d like to add a simple text field on the dashboard that would display the value of the field on the front end of the site.

For example, on the dashboard (in the admin bar would be great, but anywhere is fine) there will be a field where a logged in user can type in a number (e.g. 195) and on the front end, in the footer in every page it will display that number with some text (e.g. “The current kit number is 195”).

Is there a plugin or widget to do this already? If not, can anyone help me out with some search terms? I’ve been searching for info, but not coming up with anything like this which makes me think I’m searching on the wrong terms. Thanks!!