Laravel validation between if checkbox checked

Laravel Version: 5.7

I want to set a validation. when checkbox is checked, then set a 'between' rule. just like below.

required|integer|between:1,2

but when checkbox is not checked is not need between rule like below

required|integer

I try to use validation, But I don't know how to set.

Inputs

<input type="checkbox" name="checkbox">
<input type="number" name="number">

via Chebli Mohamed