If you love KPIs, here is one. The attractiveness of your (corporate) function is defined by the number of people who want to join you. No queue, bad news. ‘Place to be’, excellent news. There is no other way.
You need to make the ‘place to be’ accessible to people who want to join you but who can’t simply abandon everything else. Provide short secondments, shadow work, job swapping, anything that can open your work to others. And yes, of course, job openings if you have them.
Make a rotation to your function very attractive. To learn new things, upskill quickly, see the world from other angles. The stay does not have to be long. You may even declare quotas. Three places for Marketing people, four for Sales, five for R&D, etc.
A gentle dose of internal competition does not hurt.
Make no apologies for the fact that you want your area to be a magnetic place. If others are envious or uncomfortable, ask them to do the same.
Create your own internal alumni and treat them like that, with appropriate reunions for example.
If you are uncomfortable with this internal marketing, I have a suggestion for you: get over it.