What is the meaning of Eyeball?

The ball of the eye.

A person's focus of attention. (Can we add an example for this sense?)

Surveillance.

A readership or viewership.

A face-to-face meeting.

A favourite or pet; the apple of someone's eye.

To gauge, estimate or judge by eye, rather than measuring precisely; to look or glance at.

To stare at intently.

To roll one's eyes.

Source: wiktionary.org