Part of it depends on culture. I'm used to
Caleb w/ a C because of En. culture, but any way you slice it, since it's brought in from Hebrew, it's more a matter of the phonics and choices of the language it's brought into... and can go either way... I prefer the C, but am tired of the name 'cause I've met too many Calebs born in the past decade and a half or so.