Traditionally, a missile homes in (not hones in) on a target. The verb hone means "to sharpen." The verb home means "to move toward a goal" or "to be guided to a target." But some usage guides now recognize hone in on as an acceptable alternative to home in on.

Examples

Ewen Calloway

Much like a heat-seeking missile, a new kind of particle homes in on the blood vessels that nourish aggressive cancers, before unleashing a cell-destroying drug.

Much like a heat-seeking missile, a new kind of particle in on the blood vessels that nourish aggressive cancers, before unleashing a cell-destroying drug. Carl Reiner

A fellow who has a funny bone can learn to hone his skills, but I don't think you can develop a funny bone: you either have it or you don't.

Usage Notes