procedure ScrollBox1MouseWheelUp(Sender: TObject; Shift: TShiftState;
MousePos: TPoint; var Handled: Boolean);
procedure ScrollBox1MouseWheelDown(Sender: TObject; Shift: TShiftState;
MousePos: TPoint; var Handled: Boolean);
private
procedure getmouse(var msg:TWMMouseWheel);message WM_MouseWheel;
{ Private declarations }

procedure TForm1.ScrollBox1MouseWheelUp(Sender: TObject;
Shift: TShiftState; MousePos: TPoint; var Handled: Boolean);
var
posi:integer;
begin
posi := ScrollBox1.vertScrollBar.Position - 25 ;
if ScrollBox1.vertScrollBar.Position < 0 then posi := 0;
ScrollBox1.vertScrollBar.Position := posi;
end;

procedure TForm1.ScrollBox1MouseWheelDown(Sender: TObject;
Shift: TShiftState; MousePos: TPoint; var Handled: Boolean);
begin

ScrollBox1.vertScrollBar.Position := ScrollBox1.vertScrollBar.Position + 25 ;

end;
procedure TForm1.getmouse(var msg:TWMMouseWheel);
begin
ScrollBox1.SetFocus ;
end;


网友补充：

只要scrollBox能获取焦点就可以。

在scrollBox的onMouseMove上设置焦点。

然后在scrollBox的onMouseWhell中：

scrollBox1.Scrollby(0,WheelDelta);