The information subpoena is a judgment creditor's best friend: written questions that banks, employers, or the debtor must answer under oath about assets.
Once you have a judgment, you serve the subpoena (with the required certification) by certified or registered mail with a prepaid return envelope. Recipients must answer in writing under oath within the statutory window.
The debtor and any third party likely to know about their assets, most often the debtor's bank (paired with a restraining notice) or employer. Ignoring it can lead to contempt.
The power to compel banks and employers comes with a judgment. Before that, you rely on public records.
Non-compliance can be enforced by the court, including contempt.
Account existence and balances (banks), employment and pay (employers), and a broad asset list (the debtor).