Hi Rachel,
I remember seeing a few Isabella Caley's during my many frequent research trips and Caley is a well known surname on the island.
If you can tell us a few more details as to her date of birth/ birth year, where she went and approx year, I'm sure that someone will assist you further.
The latest Isabella Caley I've came across (whilst looking for Thomas Wade), was Isabella Ann Caley, born in Lezayre about 1871 and was in Kirk Bride at the time, residing at Ballavarkish.
Reference 1891 Census, RG12/4684 page 99