Collapse the poles to the maximum extent possible. Consider taking the segments apart if possible, to further reduce their overall length. My Leki poles are about 3-inches shorter when I take the telescoping segments apart and rubber band them together. They should fit inside your rucksack.
If they do not fit inside the rucksack, fasten them to the side of the pack using the available lashing / compression straps and side pockets. Wrap paper towel or something else (a Camino clothing item) around the ends that are in the mesh stretch pocket so as not to puncture it during handling. The airline baggage system can be rough on all luggage.
Place the rucksack in a cheap nylon laundry bag. I buy mine in the local dollar store, I actually paid USD one dollar for a fine mesh nylon bag that does not snag on the luggage handling system, and weighs almost nothing, literally. I recommend buying the loudest, brightest color you can find, so identifying your bag in a baggage area will not be a problem, and no one would think of trying to walk off with a so easily identifiable bag.
Tie the laundry bag securely shut, with a destination luggage tag affixed, telling the airline who you are and where you are staying your first night. I have the practice of staying in rented lodgings for one or two nights on arrival anywhere, before I start a Camino. Place a copy of the destination tag attached to the rucksack, inside the laundry bag. If you and the bag are separated, you want the bag and rucksack to get to where you will BE for the next night or two, not where you came FROM.
Just check the bag. I have done this on my past four Camino trips from the US to airports at Brussels, Paris and Madrid. It works just fine. Even if you have to pay to check the bag, the cost is far cheaper than if you tried to by the same or similar hiking poles in Europe.
On arrival, the laundry bag can be used as a rucksack liner, laundry bag, trash collection bag for along the Camino (if you are so inclined to give back), a lower leg and foot cover for sleeping in a cold albergue in chilly weather if you do not have a sleeping bag, and to contain your rucksack and poles on your return journey.
I hope this helps.