The Sample Extractor is a machine owned and used by the Galactic Armada. This tool is a short metal rod with a pill-shaped end that opens up to reveal a syringe used for extracting various liquids.
It is first seen taking a sample of Stitch's blood in Lilo & Stitch. The syringe is detachable to allow Galactic Armada officers to use the extracted example for any purposes, and likely may also allow them to switch syringes if necessary. In the case of the syringe with Stitch's blood in it, an officer took the syringe and inserted it into a machine that analyzed the blood's DNA, allowing for two plasma cannons on the ceiling to track Stitch's genetic signature and fire at him should he escape. However, Stitch quickly exploited a weakness in the tracking just shortly thereafter and used it to escape.