How to auto populate the values of custom field in 'Performance Appraisal' from custom field's value of 'Self Appraisal'

How to auto populate the values of custom field in 'Performance Appraisal' from custom field's value of 'Self Appraisal'

I am having two custom fields in self appraisal form and two custom fields in Performance appraisal. when a self appraisal is submitted, then the values of those custom fields should be pushed into the custom fields of Performance Appraisal. How to do that.