Scattered around space are fields of debris from ancient ships and stations. Ships may be deployed to scan these locations to see what of use, if anything, may be acquired.
Any flagship has the required sensors to scan debris. Scanning will occupy the vessel for 1 minute. Simply select the flagship, right click the debris, and choose 'Scan'.
Once fully scanned a variety of options may be seen in the detailed view of the debris. Which options are available is dependent on what created the debris, and luck. Although most debris will have at least some value, not all debris will contain something of serious interest.