Drop Down List - Return Item Code Only

I have made a dropdown list of my billing codes where I can search for a task and then view all of the available billing codes for that task. 

However, I would like to be able to add this list to a cell and just return the 4 digit billing code. For example return "9015" when I select "Basic Plan Review (Flat Fee).

I have the list in two formats. One is a table with t billing code in once column and the description in another and the other is in one column where the code and description is combined.

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