You must wait 21 days after your small claims judgment was signed before you can file a discovery subpoena. Form MC 11, Subpoena (Order to Appear) can be used.
Contact the court for an appearance date before putting the date and location on the form. Complete both the front of the Subpoena and the Affidavit for Judgment Debtor Examination on the back. The judge must sign the Subpoena before it's effective. Once the Subpoena is signed you must serve it on the defendant.
The fee for filing the Subpoena with the court varies. The cost of serving it also varies. You may include a copy form DC 87, Affidavit of Judgment Debtor, with the Subpoena for the defendant to fill out.