Hello Kajal

You can pursue BA after completing diploma but you won't get lateral entry .

There are few colleges that allow to pursue Bachelor of arts course after diploma , most of colleges offer courses like bsc , bca and bachelor of engineering after diploma in engineering.

You will get a BA seat in the first year of this three years undergraduate program after diploma course in some  universities of karnataka.

Both fields are different fields.  You may get lateral entry to BCA ,Bsc /IT in MK university madurai after completing diploma in engineering.

Eligibility for BA - The candidate must have passed std xii with minimum 50% marks from any reputed university .

Colleges for BA course

Delhi university

Somaiya college of arts

Vivekananda college of arts , commerce and science