PL/SQL Sysdate to format

Hello experts,

Need to insert date into Oracle DB.

MERGE INTO tmp_case_insrt_fnl_b tmpb
    USING tmp_case_insrt_fnl tmp
    ON (tmpb.crm_case_id = tmp.crm_case_id)
  WHEN MATCHED THEN
    UPDATE SET tmpb.CRM_REQUEST_DATE = sysdate

This inserts 26-JUN-18.
Other tables in the schema have dates like
26-JUN-18 11.29.01.033000000 AM

Have found some tracts  on the net
that use 'DD-MON-YYYY HH24:MI:SS'
This gives military, twenty-four hour
for the HH.

But none that provide the format with
fractions of a second out to nine digits and
the meridian (AM or PM) indicator.
Can't use TOCHAR because the field wants
a date format.

Thanks.

Allen in Dallas