Don't know a widget for this but you can easily create two microflow buttons for this. 1 that does the attribute number + 1 and a microflow that does a -1. Add a icon or glyphicon(arrow down) to let the user know what the button does.
You can follow what Maarten has mentioned by styling your input widget with icons and microflows.
Or, you can also look in the widget https://appstore.home.mendix.com/link/app/48786/ if it helps.
This is not exactly what you need with input fields, but has a slider that increase the number and you can call a microflow with which you can set the number.