The simplest approach is to create a table for storing your values. Place your code in one field and the matching name in a second field.
You can then specify your value list to draw its values from the code field in column 1 and display the matching name fields in column 2. When you select a value from the list, just the code will be entered into the field.
If you format your field to be pop-up menu with this value list. You'll see the name displayed, but will be entering/storing the code number into the field.