SQL>DESC TEST;
 Name                                                                                                              Null?    Type
 ---------------------------------------------------------------------------------------------------
 TESTCOL                                                                                                                    VARCHAR2(50)

SQL>CREATE OR REPLACE PROCEDURE TEST_PROC
  2  AS
  3  BEGIN
  4   DBMS_OUTPUT.PUT_LINE('This is the test procedure');
  5  END;
  6  /

Procedure created.

SQL>BEGIN
  2  TEST_PROC;
  3  END;
  4  /
This is the test procedure

PL/SQL procedure successfully completed.

SQL>CREATE OR REPLACE TRIGGER TEST_AI
  2  AFTER INSERT ON TEST
  3  BEGIN
  4   TEST_PROC;
  5  END;
  6  /

Trigger created.

SQL>INSERT INTO TEST VALUES('ABC');
This is the test procedure

1 row created.