Got it, in that case instead of attempting to monitor for job changes as they happen, it would be more effective to simply enrich these contacts' LinkedIn profile in which you can then view data around their work experiences. The key here being you'll be able to see start and end dates of their work experiences and determine if they've changed jobs in the last year or so.
Hope this was helpful, let me know if you have any other questions surrounding this. Happy to help you set this up. :)