No, you cannot apply for the CA Foundation exam while currently studying in 1st PUC (first year Pre-University Course).  The eligibility criteria for the CA Foundation exam typically require you to have completed your 12th standard education.

You need to pass your 12th standard exams from a recognized board (in any stream - Arts, Commerce, Science) with a minimum of 33% marks. Since you're in 1st PUC, you haven't completed your 12th standard yet.

Focus on your PUC studies and aim to score well. You can apply for the CA Foundation exam after completing your 12th standard and meeting the eligibility criteria.Explore the National Institute of Open Schooling (NIOS) option. NIOS allows students to complete their 12th standard through open schooling, potentially enabling you to appear for the CA Foundation exam earlier (depending on NIOS exam schedules).

https://finance.careers360.com/exams/ca-foundation-exam

I hope it helps!