Schroeder's comment to your question implies the answer: No.
To get to your specific question, a malicious network can see only your network traffic. You can install something like Wireshark to see what traffic you are sending. That's what a network operator can see.
But that's a conditional "no." There is software that will allow screen sharing, i.e. snooping, and if such software is running on your computer, whether because the computer belongs to the company and they've installed it, or because it was installed surreptitiously, then yes. Unless the software is pretty sophisticated, you'd be able to see the screen sharing traffic with Wireshark, and you could certainly see it with an external network monitor.