The Digiscanner is an instrument in GTA 5 that appears in a few cutscenes in the game. It is used by Michael at one point in the mission ‘Chasing The Truth’. The Digiscanner is an instrument and not exactly a weapon as it does no damage. It is a handheld item.
The Digiscanner is most likely based on the P.K.E meter from the Ghostbusters franchise. It has a T-shaped antenna at the top with wiggling arms, a digital screen which gives a reading, and buttons below it. It has a handle with a grip and two extra V-shaped antennas behind the T-shaped antenna.
The Digiscanner does no damage and only shows a reading when it is in range of any alien object. It is given to Michael for him to find an alien artifact. It is also seen being used by Omega to scan Franklin and says that he is a carbon based life form, while he mentions other things deducted from his scan.
This device appears in the Epsilon program mission “Chasing The Truth” where it is handed over to Michael De Santa to search for an alien artifact.
It is also seen in the hands of Omega during the Strangers and Freaks mission “Far Out” for Franklin Clinton. Omega uses the device to scan Franklin.
The unused Ammu-Nation description suggests that LSPD officers use it to scan vehicles’ license plates. This also suggests that it would be available in the gun stores at some point or as part of a setup mission, much like the Remote Sniper.
Since Michael receives one from Marnie Allen, it is possible that the Epsilon Program uses it in their activities.
The implied use of the Digiscanner by the Epsilon Program seems to be a reference to the use of E-meters by the Church of Scientology, a religious cult the Epsilon Program is based on.
The Digiscanner was later adapted to Red Dead Redemption 2 as the "Electrostatic Detector" used during the mission A Bright Bouncing Boy - II, and in Grand Theft Auto Online as the "Metal Detector" used during the Cayo Perico Heist preparation mission Heist Prep: Gather Intel.
A. The Digiscanner only appears in mission cutscenes and is given to Michael to use in the mission Chasing The Truth. Other than that, the Digiscanner cannot be obtained or used in GTA V.
A. The Digiscanner is an instrument in GTA V used to scan alien life forms by the Epsilon Program and Omega.
A. The detector is actually a Digiscanner as mentioned in the game files. It is an instrument featured in the game that beeps and gives a reading when close to an alien life form or object.