Install the latest Wacom driver and perform the following steps:
- Go to System Preferences > Security & Privacy.
- Go to the Privacy tab, select Accessibility and then click the lock icon at the bottom of the dialog box.
- In the Allow the apps below to control your computer list, ensure that the checkboxes for Wacom component are selected. Also, ensure that any known listed applications are also selected to work correctly with the tablet. For example, Illustrator, Photoshop.