how to get all object in a picklist and based on the selected object its fileds should populate in lightning?

hi, i am new to apex trigger. can anyone please help me?

ok now, i have a custom field on account that is 'ID'
now i want to write a trigger in account so that whenever i create a record in contact, the contact id will store its id to my custom field 'ID'... please help me out. 

hi, i am new to apex trigger. can anyone please help me?

ok now, i have a custom field on account that is 'ID'
now i want to write a trigger in account so that whenever i create a record in contact, the contact id will store its id to my custom field 'ID'... please help me out.