As for as I know some salespersons use this strategy to do B2B sales through linked in:
If you already worked with a person and the person moved to another company, you can reach him out and offer your services to his new employer.
So, my idea is:
A service to check weekly who among your contacts moved to another company and send this list.
What do you think about this idea?
Agree with @watus here. There's also this tool jobtitle.io but they're still in beta. So whether this can work as a standalone tool needs to validated.
Similarly, previous contact or not, a new executive most likely has the motivation to make an immediate impact on his/her role. Sales navigator also shows who've changed jobs in the last 90 days.
Sales navigator does that for the contacts you have "saved", pretty powerful feature for sure, would need to see how you can complement the offer