Your mortgage lender will send you a Form 1098, also called a mortgage interest statement, by February 1 following each tax year. This should detail how much you paid for interest, principal, mortgage insurance, and more across the year. You can use this to calculate your various deductions.
Most lenders send these forms via snail mail, though you may be able to download yours online, too. Check with your servicer to see if they offer an online dashboard or customer center you can utilize.  If your loan is serviced by Rushmore, visit this link to learn more about how to access your 1098.