Questions about two medications?

There is a moderate interaction between both meds, moderate meaning:

Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.

Interactions between your drugs
Moderate
lisinopril methylphenidate
Applies to: lisinopril, Ritalin (methylphenidate)

Methylphenidate may cause an increase in blood pressure and may diminish the effects of lisinopril on blood pressure. Contact your doctor if your condition changes. If your doctor does prescribe these medications together, you may need a dose adjustment or need your blood pressure checked more often to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

More info, 2 moderate food interactions:

https://www.drugs.com/interactions-check.php?drug_list=1476-0,1606-979

If the same Dr. prescribed both medications, most likely he/she is aware of these potential interactions and has outweighed that the benefits are greater than the potential risks.
Now, if these meds were prescribed by 2 different Drs. and they are not aware you are taking 1 or the other med, do not take them until you inform them, and get their medical advice.