Need help with new custom fields

So I have tried all the settings when creating a new field, I looked through all of the add-ons and found none that would do what I want to do and there does not appear to be any documentation online anywhere for this plugin. I am very surprised that this plugin does not have an online FAQ, or any sort of documentation. I cant find it anywhere, even googled it.

Ok so what I want to do is create a new field that the User can not edit or enter data, only the admin or agent can edit the field. I am trying to create a field for each ticket called “Support Hours”. The field will allow for Admins and Agents to edit the field so the customer, or client, will see how many support hours that ticket requires to fix the issue.

Is this possible with or without any addons? I cant seem to figure this one out.