Although cable needles designed for miniature knitting are available, they are not easy to find. The easiest and most commonly available substitute is a tapestry needle.
Tapestry needles come in the same sizes as the old UK needle sizes used in miniature knitting. Tapestry needle sizes 16, 18, 20, 22 and 24 are commonly found in sewing or craft shops and haberdashery departments. Tapestry needle also work because they do not have a very sharp point, so may be used to transfer stitches easily without splitting yarn.
If a larger size than 16 is required, then a wooden cocktail stick is roughly equivalent to a size 14 UK/2.00 mm/US 0. However if you do need to use a cocktail stick, it may be best to smooth the surface with sand/glass paper or rub it gently with an emery board, to avoid rough edges snagging on yor work.
A steel paper clip (opened out) may be used, but again check the ends are not rough and DO NOT leave this in your knitting for any length of time, as it may rust and this will be transferred to your yarn.