How does [発見]{はっけん} function here?


I couldn't find any explanation online anywhere, and I see it being used a lot
as such an expression "[something] [発見]{はっけん}", like "shield is found." in
Apex Legends game for example, and in some anime "いい[棒発見]{ぼうはっけん}", being
another example.

Isn't it a noun? How is it being used here on its own, instead of its verb
form? Because of its tone I wonder whether it's originally a military
expression?

