How to retrieve data from Client Dashboard Item and display it using different ASP.NET controls

To request data displayed in the specific Dashboard Item, you should call GetItemData methods of the ASPxClientDashboardViewer object. 
Then, you need to iterate through the item's elements (rows, cells, points, etc ), collect information about corresponding dimensions and measures and store it as JSON collection. You can send this collection to the server in a string format using the JSON.stringify Function. To parse the string on the server, you can use the Json.Decode Method. 

Note that if you wish to display an underlying data source data, you can use the RequestUnderlyingData method instead of the GetItemData one.