Detail this asset from Unity Asset Store: Original Link
This is a paid asset, but now you can download Realistic Eye Movements Free.
Realistic Eye Movements v2.1.1 (Latest version)
Realistic Eye Movements v2.0.1
This easy to use component makes your characters more lifelike by animating their eyes, heads, and eyelids. It uses human movement data from published academic research to produce convincing eye animation.
It has additional support for usage in virtual reality (VR) projects and is used in VR titles such as Technolust. It is the code behind the VR demo Coffee without Words. It lets the character look at the player’s “social triangle”: each eye individually and the mouth region.
If your character was generated with Adobe Fuse (Mixamo), MakeHuman, Autodesk Character Generator, MCS (Morph3D), Reallusion’s Character Creator 3, or UMA, setup is as easy as just importing the corresponding preset with a few clicks. For other characters, setup is simple as well: just assign the corresponding bones or blendshapes and set a few eye positions like looking up or down.
You can let the character look around randomly, at the player, or at points of interest that you defined and which you can control. Works on desktop and mobile.
The asset comes with full source code.