On any Object within the system you can create a Formula field to display the 18-digit Salesforce Record ID for each record on that Object.
The System Administrator User will navigate to Setup Create > Objects
In this example, we will create the Field on the Staff object.
Under Custom Fields and Relationships click the New button
Choose a Formula field
Data Output Type of Text
The formula you will use is: CASESAFEID(Id)
Save the new custom field.
To make the field visible on the page, you'll need to add the field to a Field Set.
See also: Adding Custom Fields to a Field Set