get categories from the main site?

I set up a multisite with 1 main site and 1 client site. they are using different themes.

the client site is more like a application added to the main site, so, although it has its own categories, i’d like to show a category list of the main site at its front end.

i’d like to use wp_list_categories() , but there is no parameter to do so.

how can it be done? i need only to show the categories and their links , not syncing it across

thanks in advance.