Code:
SQL> create table my_table(my_comment VARCHAR2(100),
  2  my_date_with_milliseconds VARCHAR2(25));

Table created.

SQL> insert into my_table values
  2  ('The time in millisecs I''ve got from somewhere',
  3  '2002-08-26 16:42:37.226');

1 row created.

SQL> select * from my_table;

MY_COMMENT
--------------------------------------------------------
MY_DATE_WITH_MILLISECONDS
-------------------------
The time in millisecs I've got from somewhere
2002-08-26 16:42:37.226