If you can’t see the mouse during a VNC session, or you can only see a dot, then the most likely explanation is that there is no mouse connected to the VNC Server. The easiest way, if you have access, is to attach a mouse to the server. If you can’t do this, then try changing the VNC Server settings as follows:
Windows 10 Users:
Enable the “Use numeric keypad to move mouse around the screen” option from Start > Settings > Ease of Access > Mouse.
Windows 7 Users:
Open the Control Panel and select Mouse. From the “Pointer Options” tab, toggle the “Display pointer trails” option on or off. Click Apply to save your changes.