This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 猧 is uncertain. It visually contains 犭 (dog) and 咼, but the original semantic and phonetic roles are unclear.
Since the meaning is unclear, focus on the shape: a dog 犭 beside a component 咼 that looks like a mouth 口 under a cover. Picture a dog barking under a strange roof.
For カ, imagine a dog barking 'ka-ka-ka' under that roof: the sound カ is the dog's call.