Extract dates from Calendar field instead of duration

Hello, I'm trying to make a "get a quote" form where some booking dates are need. I can't allow for booking in past so I choose Calendar filed with that option. On last page I would to make some summary before user send it but when I put Input field with default value with ID of calendar field, I'm getting a duration between that dates instead of start and end date. How can I reach that?

Also after sent a form there will be only duration to in email?

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