What preposition should be used with "cache"?

To cache something means to store it away, so I think the most natural preposition is in. Cached on is also fairly common.

Cached to is very uncommon, but appears to becoming more popular in software contexts. I suspect this is because non-software caches usually require you to be close to them, but software caches are often remote so that the act of caching involves sending data to another server. Because your phone is not a remote server cached to is an unnatural choice.

You can see the relative uses of these prepositions with Google Ngrams.

To cache is to store something away for future use (especially if in a hidden place). You could store things in a box or on a shelf but I can't think of any situation in which you'd store something to somewhere. One normally talks about storing things on a particular computer/disk/memory stick so I would use the same for cache.