Hi Ine,
It can be achieved by creating a dynamic segment with a behavior block.
Here is an example, which can filter out the contacts who unsubscribed from a subscription list (Subscription 01).

After going live it, you can see the total number of unsubscribers and details of them in members tab.
Of course you can also add restrictions on Customer Journey or Email to the conditions to filter out people who have unsubscribed through a specific Customer Journey or Email.

If this helped you, I'd appreciate it if you'd mark this as a Verified Answer, which may in turn help others as well.
Best Regards,
Nya