How to display Extract Date/Time in Tableau Dashboard

Since we cannot add any calculation in the tableau dashboard and the extract date is available in worksheet only at two places one in the Title of the worksheet and the other in the caption. So In order to display it in the dashboard you need to first create a worksheet with <Date Update Time> embedded to either title of the worksheet or the caption.

One more thing to keep in mind is the value for <Date Update Time> will be displayed only when you use some field from the datasource on the worksheet or else it will not show me any date. See below screenshot to get a better understanding of how the date will be seen when there is no data

So just drag one field onto either row or column shelf which will show us the date field value as below:

Now you need to add this worksheet in the dashboard and display it wherever you want using the floating feature. Also remember since here I am using the date field to be displayed in the caption once you drag and drop this worksheet in the dashboard you will not be able to see the date value. You need to right click on the worksheet and select "Show Caption". You need to do some formatting for hiding the data on the worksheet so that only date value will be displayed.