SQL> CREATE OR REPLACE FUNCTION dumb_function
  2     RETURN NUMBER
  3  IS
  4     vResult         NUMBER;
  5     vDumbVariable   dept.deptno%type;
  6  BEGIN
  7     SELECT count (*)
  8       INTO vResult
  9       FROM emp;
 10  
 11     RETURN vResult;
 12  END dumb_function;
 13  /

Function created.

SQL> SELECT referenced_owner, referenced_name
  2    FROM user_dependencies
  3   WHERE NAME = 'DUMB_FUNCTION' AND referenced_type = 'TABLE'
  4  /

REFERENCED_OWNER               REFERENCED_NAME
------------------------------ ----------------------------------------------------------------
SCOTT                          DEPT
SCOTT                          EMP