With the new Way of Life DLC, if you have Intrigue Focus, you should be able to Spy On other characters.
For characters where the Spy On is available (greyed out or not), the requirements are listed as:
- is not a prisoner
- is an adult
- is within diplomatic range
But for many characters, Spy On is not available:
What are the requirements for that?
Based on my observation it seems that I can spy only on characters in my realm. Is that correct?