i have paramenters in my jquery function which has to get the value from controller but i am unable to get the value from controller by hitting the controller

how can i hit the controller and get that value from controller 

var searchCriteria = {};
searchCriteria.CareTeamId = $("#ddlCareTeam :selected").val();  
//fetching the first value at zero index instead i need to hit the controller and get that value