I must warn , its most likely to be a scene that has happened in various titles, so if you have an aproximate chapter number as well it would help a lot. Here is what i remember: MC's subordinate was sent to investigate several people, when he came back to report to our MC he was happy he found out many details, but he didnt realize that most of the folks had instead planted tracing marks on him , which i think the MC told him and removed them after that. Thats about it, hope its not too common occurence.
It kind of sounds like something that happened in Bringing The Farm To Live In Another World , I know I read it before Armored Raven started translating it since I stopped reading it before he picked it up. Not sure if it's the right novel and can't really help you with which chapter, but if you haven't read it I can highly reccomend the first 100 chapters.