Find values in a 3D array based on values in a seperate 3D array

I have two seperate 3D arrays that have equivalent sizes. One array (M_data) is binary. If the value of an element =1, I'd like to save the value of the corresponding position from the second array (B_data) in a matrix. So far, it looks like my code is giving me the i,j,k positions of M_data that equal 1, but it isn't referencing the B_data and it's not saving any of the data to a matrix. It's been a while since I've worked in Matlab and frankly I was never much of an expert, so any help would be much appreciated.

for i=1:size(M_data,1)
    for j=1:size(M_data,2)
        for k=1:size(M_data,3)
            if M_data(i,j,k)==1
                
               output= i,j,k, B_data(i,j,k);
                
            end
        end
    end
end

Answer 1

[Andrei Bobrov]

lo = M_data == 1;
[ii,jj,k] = ind2sub(size(M_data),find(lo));
output = [ii,jj,k,B_data(lo)];

[KS]

Thank you Andrei!! That worked perfectly.