Get a Field's ScriptID

I have a custom record set up with a custom field of type 'List/Record' and the list selected is 'Field'.  So this custom field is a drop-down of NetSuite fields.

When I do nlapiGetFieldValue() on that custom field I get an internal id returned (i.e. '8332').  Is there a way to get the field's ScriptID (i.e. 'custitem...')?

Or is there a way I can use the internal id returned to get the value in the field selected?  For example, if the field selected were the Display Name from an item record, when I do nlapiGetFieldValue() on the custom field on the custom record I get '-1099'.  Is there a way to use that value to look up the Display Name on the item?  I have tried nlapiGetFieldValue('-1099') and it simply returns null.  nlapiGetFieldValue('displayname') returns the correct value.