I suppose you have already had your collection/array, here is the detail for what I commented as suggestion:
public class Item {
public string FullName {get;set;}
public string ID {get;set;}
}
//your array of Item
Item[] items = ...
//Bind your array to your combobox
comboBox.DataSource = items;
comboBox.DisplayMember = "FullName";
comboBox.ValueMember = "ID";