What happens to equipment purchased using a startup package after an academic leaves the university?
What happens to your stuff depends on how your university classifies it. Inventoried material—more expensive items that a university keeps track of—will almost certainly need to be accounted for. So that probably includes laptops and tablets, unless they're so old they've been removed from inventory (as not having any significant value anymore). Major laboratory equipment and furniture also fall into this category. Such materials will probably be held as "surplus," and made available to other groups or departments.

In contrast, small-ticket items—such as stationery and miscellaneous office supplies—are not normally tracked. You won't be asked to reimburse the university for a missing stapler.