Basic probes return again in Homeworld 2, with essentially the same function as they posed in the first game. These units can be moved to a single location, where they become permanently immobile. Their benefit comes from incredibly cheap cost while granting massive sensor range. It’s always a good idea to build 4-5 of these early on in a level or multiplayer match to establish a sensor grid around your Mothership or Carriers. This will give you advance warning of approaching enemies. Make sure you take out your opponent’s probes in order to blind them.
If you do not move a probe (including he variants below) after it is built in the main campaign, it will come with you to the next mission, however if moved, will be left behind. Building one and just leaving it next to your Mothership, Carrier or Shipyard can be seen as a poor man’s advanced sensors module.