use Samsung monitor with Mac Air
How do I use my mouse connected to Mac Air and Samsung monitor?
MacBook Air 13″, macOS 10.13
Without knowing more details about your configuration, it's impossible to say.
If you are trying to plug a wired mouse – or a USB receiver for a third-party wireless mouse – into a downstream USB port on the monitor, then you will need to establish an upstream USB link between the monitor and the Mac. This is usually done over a dedicated USB-A or USB-B link, or as part of a USB-C connection. See your monitor manual for details.