C # capture mouse wheel events to achieve google earth zoom in and out.

Why do you think you need a Hook? You just need to handle the event System.Windows.Forms.Control.OnMouseWheel:

MyControl.OnMouseWheel += (sender, eventArgs) => {
    GoogleEarth.ZoomBy(eventArgs.Delta); //or whatever you do for zoom, see below
}

I see you also want to use C# v.2. In this case, the lambda form will not work. You need to use older syntax:

using System.Windows.Forms; 

//...

MyControl.OnMouseWheel += delegate(object sender, MouseEventArgs eventArgs) {
    GoogleEarth.ZoomBy(eventArgs.Delta); //or whatever you do for zoom, see below
}

In this form you need explicit declaration of the delegate arguments as the type inference was not yet introduced in C# v.2.

The property Delta here gets a signed value of the wheel rotation which caused the event. For more detail, please see:
http://msdn.microsoft.com/en-us/library/system.windows.forms.mouseeventargs.aspx[^].

—SA