D5でよければこんな感じでできるかな

procedure TForm1.FormCreate(Sender: TObject);
var
s, s2: string;
i: Integer;
begin
s := 'ABC'#13#10;
s2 := '';
for i := 1 to Length(s) do
begin
s2 := s2 + IntToHex(Ord(s[i]), 2);
end;
ShowMessage(s2);
end;