Microprobe
A microprobe was a type of small probe carried aboard Federation starships that was used in cases where conventional probes were too large to be effective. 

While inside a nucleogenic cloud being in 2371,  launched a class 4 microprobe. ()

Later that year, Voyager launched a microprobe into a micro-wormhole to trace its subspace bearing, but the probe became lodged in a gravitational eddy inside. Harry Kim subsequently modified the communication system so the probe could act as a subspace relay station, allowing Voyager to make contact with the Talvath on the other side. The probe was eventually crushed by the wormhole's collapse. ()

de:Mikrosonde
Probes