Jeremy Herve on "[Plugin: Jetpack by WordPress.com] Contact Form Placeholders"

the Required Caption where you cannot apply any styling

You can style that caption by targeting the span, like so:

.contact-form div label span

Jetpack actually comes with some default styles to add a little space:

.contact-form label span {
    color: #AAA;
    margin-left: 4px;
    font-weight: 400;
}

To add more space, you can try something like this:

.contact-form div label span {
	margin-left: 50px;
}

`

I hope this helps.