DUMP function is useful for this purpose.

SQL> select dump(C1) from test;

DUMP(C1)
---------------------------------------------

Typ=96 Len=4: 48,49,53,48
Typ=96 Len=4: 48,48,49,48
Typ=96 Len=4: 48,48,53,48
Typ=96 Len=4: 48,49,48,48

Where : 
  Typ is Oracle data type ( In this case CHAR ), Len is data length. By default, the trailing numbers are stored data in decimal.

Users can add base number as second parameter.

SQL> select dump(C1,16) from test;

DUMP(C1,16)
------------------------------------------------

Typ=96 Len=4: 30,31,35,30
Typ=96 Len=4: 30,30,31,30
Typ=96 Len=4: 30,30,35,30
Typ=96 Len=4: 30,31,30,30

And if second parameter is 10xx, character set information will be displayed.

SQL> select dump(C1,1016) from test;

DUMP(C1,1016)
--------------------------------------------------------

Typ=96 Len=4 CharacterSet=JA16SJIS: 30,31,35,30
Typ=96 Len=4 CharacterSet=JA16SJIS: 30,30,31,30
Typ=96 Len=4 CharacterSet=JA16SJIS: 30,30,35,30
Typ=96 Len=4 CharacterSet=JA16SJIS: 30,31,30,30

Note that the DUMP function does not support LOB data.