I dealt with squirrels by hanging one of the vertical feeders with compartments using a fairly long cord/chain from a limb...or in my case, the gutter of the house.
Then I got a square piece of aluminum sheet, about 12-15 inches square-more if possible...(not foil..just thin metal)... and poking two holes in it spaced like the hanger wire of the feeder. I thread the hanger wire thru the sheet of aluminum and hang it up. The roof of the feeder is pointed, so the sheet has no flat support.
A squirrel who tries to go down the chain finds this wobbly barrier in his way, and gets VERY frustrated. (I have seen one hang by his back toes and reach around the edge and barely manage to grab a feeding perch and swing around the barrier, but mostly they either didn't try or slipped off. A bit wider sheet would have made it impossible.
   Occasionally a squirrel will take a flying leap from another limb, but they usually don't manage to grab the feeder....and we get the entertainment of watching them contemplate and try various methods.