Display field in an Link

Hello, i wish to know how to select the field to be displayed as options in the linked field. for example if i create a form capacity(capacity_name, capacity_title) and create a link with room_capacity, how to i display make capacity_name to be what is displayed as options in room_capacity field. the default currently displayed is the field ‘name’ done automatically by frappe.

You will have to make additional fields that will “fetch” those quantities on select.