Set OR Get apex item value

Procedure to set the apex item value

create or replace PROCEDURE PROC AS
BEGIN
    APEX_UTIL.set_session_state
    (
      p_name => 'P1_X',
      p_value => 'KARTIK');
END PROC1;

Here P1_X is the item name which is unique in APEX.

And call this procedure or also function in apex process.

Same way you can get the apex item value using get_session_state function:
 

APEX_UTIL.GET_SESSION_STATE (
    p_item    IN   VARCHAR2) 
    RETURN VARCHAR2;