In macOS 12 Monterey, Apple added a mouse pointer customising feature. Here's how to do it.

On macOS 12 Monterey

First of all open System Preferences. Now go by the path: Accessibility > Display > Pointer. Now you'll see this window:

On macOS 13 Ventura or later

Go to System Preferences, click Accessibility on the Side Bar, then select Displays in a menu that has just appeared and scroll down to pointer.

Now you'll see something similar to the window displayed higher.

You have the pointer outline color and the pointer fill colour. The pointer outline color is white by default - this is a.k.a. a border color of the pointer shape. The fill color is black by default - this is a color which is inside the mouse pointer shape.