Yes, airlines carry both removable, and non-removable (sealed or only emergency purposes) torches. One uses the the removable ones for the walk around.
Yes, a pilot must carry a torch. An iPhone light indeed covers this requirement. However, most professional carry a small, tactical/high lumen torch for this purpose, as usually they are FAR more effective on the walk around than the knackered airplane torch.
Nothing to see here, move along.