Who told you those deductions were specifically to pay for your state pension?
The HMRC website implies it as it tells you how many qualifying years of NI you have paid and how your pension changes depending on the number of years.
Your National Insurance record
You’ll usually need at least 10 qualifying years on your National Insurance record to get any State Pension. They do not have to be 10 qualifying years in a row.
https://www.gov.uk/new-state-pension
If that's not advising that some of your NI is used for your pension then why have a correlation between NI years paid and pension due?