There are a couple of ways you can collect this information:
1) Create a custom form (admin > Forms) asking for this information and making it required. Then, you can add that form to your product page (Admin > Sites > Products > choose product > Forms Tab). Doing this will add this question on the product page and not let the customer proceed to the shopping cart without a response.
2) Use the "Acceptance Text" field on the product page (Admin > Sites > Product > Choose Product > General Tab > Product details page). Set the "I accept" Requirement to Text and add a prompt in the "Acceptance Text" box. Again, the customer will not be able to proceed to the shopping cart without entering something in the text box.
In both these situations, the answer will be on the order detail for your staff to see.