A family of Microsoft word processing software products for creating web, email, and print documents.
Hello seallen,
Sorry for the inconvenience caused by this feature.
A black circle under the cursor is a tap handle to make it easier to choose the cursor with your finger or pen. This feature enables if you use touchscreen with your device.
Please check Windows Control Panel > System and under the System heading look if Pen and Touch has a support for your device.
Unfortunately, there is no option to disable this feature for Office applications. We apologize for the inconvenience. To address your concern about the situation, we’d suggest you go to provide your feedback via clicking File > Feedback in Word. This is the best platform to let developers hear from you and make products and services better for you and others.
As a workaround you may disable your touchscreen in Windows. For your reference: Enable and disable your touchscreen in Windows (microsoft.com)
Best Regards,
Igor