This is a complete layman's question. Online etymology dictionary says about kaaba:
1734, Caaba, cube-shaped building in the Great Mosque of Mecca, containing the Black Stone, the most sacred site of Islam, from Arabic ka'bah "square house," from ka'b "cube."
The etymology of cube is traced to ancient Greek in the same dictionary:
1550s, from Middle French cube (13c.) and directly from Latin cubus, from Greek kybos "a six-sided die,"
I don't have any training in linguistics. But I know that Greek is an Indo-European language while Arabic is a semitic one and the similarity of the word for cube is striking. Is it just a coincidence, or did one language borrow from the other?