How to query multiple collections from one algolia search

I've got two collections in firebase: items and users. Each document in items contains details of an item, including the owner UID. The owner UID corresponds with the document IDs in users. Each document in users includes fields for name and postcode.

Here is the list view (there is a search bar above). The [nameortitle] and [first list item] fields are working correctly to return the relevant info from items. I want to show the name and postcode of the owner of each item in the list view - how can I set up the search without adding user information to each document in items?