How to convert post title to custom field?

Researched this for hours and came up with nothing, hoping someone here can help me or at least direct me to the right place.

I have a few thousand posts that i’d like to have its title converted into custom fields

Tried using wordpress template plugin with the value “<?php echo get_the_title($ID); ?> ” but that didn’t work. there is a way to overcome that however i don’t feel save allowing php in custom fields so anyone have any ideas?

Thanks for any help.