From the Chart Tools toolbar, click on the Sticky Crosshair tool. 
Click anywhere on the chart to display the crosshair and Data View window.
A "sticky" crosshair will remain on the chart at the point where you click with your mouse. Clicking on the chart will activate the Data View window, which can be moved anywhere on the chart.
Note: If you do not want the crosshair to stick to the chart, using the Cross Tracking option found in the Tracking tool.
To add the Sticky Crosshair
From the Chart Tools toolbar, click on the Sticky Crosshair tool.
Click anywhere on the chart to display the crosshair and Data View window.
To deactivate the Sticky Crosshair
From the Chart Tools toolbar, click on the Select Arrow 
or hit the ESC key.