Question: I accidentally left my smartphone on my bed on Friday night. Was I allowed to move it?
Answer: The Shulchan Aruch (OC 308:3) writes that items that are primarily used for prohibited acts (keli shemalachto leissur) can be moved on Shabbos if one needs the space. Thus, one can move a hammer on a bookcase to access books or from a chair which one wants to sit on. This doesn’t apply, however, to items that are muktze machmas chisaron kis, muktze for fear of financial loss.
Where one is very particular about an item, be it an expensive item or a delicate tool, etc. it takes on a higher level of muktze. Unlike regular muktze items, such items are not used for other functions. Thus, craft knives and expensive electronics cannot be moved just because they are in the way.
Seemingly, smartphones would fit into this category, and thus may not be moved in a regular way.
The Mishna Berura (309:10) writes that in such a scenario, the muktze item should ideally be tilted off by lifting the base. Thus, one may lift the covers (or mattress) allowing the phone to fall. If the phone is on and doing so may cause a button to be knocked, or if doing so may cause damage to the phone, then one may lift the blanket with the phone on it and place it down elsewhere.In conclusion, while the phone may not be moved normally, one may either lift the covers to shake it off or if necessary, lift the covers off and place them elsewhere.