Javascript and asp.net [vb] webforms session

I have a javascript method that returns a string, In case:

var hash = PagSeguroDirectPayment.getSenderHash();

How to put this hash variable in a session and read this session in asp.

Dim hash as string =  Session("sessionDoHashExemplo").toString

Or there is another way (without using post / get) to pass this information to asp.

The above code is in a separate .js file, and I can not use an input hidden