using EntityFramework.Expand.ProcedureCore;
using System.Data;
  /*Sample*/
  public class usp_helloworld
  {
    [EntityProcedure(System.Data.SqlDbType.Int)]
    public int p1 { get; set; }
    [EntityProcedure(System.Data.SqlDbType.VarChar, 20, ParameterDirection.Output)]
    public string p2 { get; set; }

    public class Result
    {
        public int col1 { get; set; }
        public int col2 { get; set; }
    }
  }

Create PROCEDURE [dbo].[usp_helloworld]
-- Add the parameters for the stored procedure here
@p1 int , 
@p2 varchar(20) output
AS
BEGIN
  -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

  -- Insert statements for procedure here
  set @p2='helloWorld value';

    SELECT 1 as 'col1','hello1' as 'col2';
    return 1
END

using EntityFramework.Expand.ProcedureCore;
public partial class MyEntities : DbContext
{
  public virtual SpListSet<usp_helloworld, usp_helloworld.Result> usp_helloworld { get { return new SpListSet<usp_helloworld, usp_helloworld.Result>(this); } }
}

        var context = new MyEntities();
        var obj = context.usp_helloworld.Run(par =>
        {
            par.p1 = 1;
        });

        //get ReturnCode from 'return 1' or other return
        var code = obj.GetReturnCode();
        
        //get list from table select 
        var myList = obj.ToList();
        
        //or search some one
        var myData = obj.Where(w => w.col1 == 1).ToList();

//DbContext
public virtual SpValueSet<usp_helloworld> USP_HelloworldValue { get { return new SpValueSet<usp_helloworld>(this); } }
----------------
//your code
//after RUN() use GetParameter() to get p2(OutPut)
var p = obj.GetParameter();
string value = p.p2;